1. Field of the Invention
The present invention relates to a sample cooling apparatus used in an X-ray diffractometer and to an X-ray diffractometer that uses the sample cooling apparatus.
2. Description of the Related Art
An X-ray diffractometer performs measurement in which X-rays are directed to a sample and the X-rays coming away from the sample are detected by an X-ray detector. It is sometimes necessary to cool the sample during this measurement. During structural analysis of a single crystal, for example, in order to stabilize the molecular structure in the single crystal sample and obtain highly reliable data, measurement is sometimes performed while a low-temperature gas, e.g., nitrogen gas at about 93 K (−180° C.) to 143 K (−130° C.), is blown onto the sample.
Patent Citation 1, for example, discloses a sample cooling apparatus for an X-ray diffractometer. In the sample cooling apparatus described in this reference, a sample-supporting component such as a glass rod or the like extends in the up-down direction within a space, and a sample is supported on a distal end of the sample-supporting component. Measurement is performed while the angle at which X-rays impinge on the sample is changed by rotating the sample about an ω axis extending in the vertical up-down direction. A gas-blowing nozzle is disposed above the sample, and the sample is cooled by low-temperature gas discharged from the nozzle during measurement.
In this conventional apparatus, the sample-supporting component is mounted on an arc stage, and through use of this arc stage, the sample-supporting component can be inclined in relation to the vertical direction while the sample remains in position on the ω axis. When the sample is rotated about the ω axis with the sample-supporting component in this inclined state, the sample-supporting component moves in rotation so as to describe a cone with the sample at the vertex thereof. A gas discharge vent of the gas-blowing nozzle is disposed above a conical movement surface described by the sample-supporting component.
FIG. 11 shows another conventional example of a sample cooling apparatus for an X-ray diffractometer. In this conventional apparatus, a sample rod 101 supporting a sample S is supported in an inclined state by an ω rotation substrate 102. When the ω rotation substrate 102 is rotated about the ω axis in order to change the incidence angle of an X-ray R1 incident on the sample S, and the sample S is rotated about the ω axis in the same manner, the sample rod 101 describes a conical surface having the sample S at the vertex thereof. A gas discharge vent 103a of a nozzle 103 for blowing low-temperature gas onto the sample S is disposed above the conical surface.
When low-temperature gas is blown onto a sample, there is usually a risk of ice forming on the sample and the sample support. However, in the conventional X-ray diffractometer described in Patent Citation 1 and shown in FIG. 11, the occurrence of ice is kept extremely low, and ice does not interfere with measurement by the X-ray diffractometer.
In the X-ray diffractometer described in Patent Citation 1 and shown in FIG. 11, the ω axis is set so as to extend in the up-down direction. Due to the need to use a power transmission mechanism that includes, for example, a worm and a large-diameter worm wheel as the mechanism for rotating the sample about the ω axis, a large space is often needed in the direction at a right angle to the cω axis. The shape of the X-ray diffractometer described in Patent Citation 1 and shown in FIG. 11 in the horizontal direction (i.e., the transverse direction) is therefore enlarged, and a large space must therefore be reserved for installation thereof.
As a result of research aimed at reducing the space needed for installing the X-ray diffractometer, the inventors discovered that the size of the installation space for the X-ray diffractometer in the horizontal direction can be reduced by changing the installation position of the ω rotation substrate 102 in FIG. 11, for example, from the horizontal position to the vertical position as indicated by the arrow Q, i.e., by setting the installation position of the ω rotation substrate 102 so that the ω axis extends in the horizontal direction.